Hi Alex,
1. No, SSH tunnel is not in our plans.
2. RDP has nothing to do with RUT's performance. You can check it for yourself if you use the generic RDP client instead of RUT-Viewer. As for the remote feature, you probably meant 'Full control' or 'View only' mode. Try to reduce the color depth a little bit, and use the 'Economode'. You will find both these settings in the 'Properties' for the connection in the RUT-Viewer.
BTW, I would recommend you upgrading to the v.5.0. :) Apart from new features, such as the Internet ID, there were numerous little fixes that were made in the version 5.0.
Thanks.